Conversion of 7,11-diketo steroids to 11-keto steroids



CONVERSION OF 7,11-DIKETO STEROIDS TO ll-KETO STEROIDS Earl M.Chamberlin, Westfield, and John M. Chemerda,

Metuchen, N. 3., assignors to Merck & Co., Inc., Rahway, N. .l., acorporation of New Jersey No Drawing. Original applications March 10,1951, Serial No. 215,026, and September 20, 1951, Serial No. 247,563.Divided and this application November 29, 1957, Serial No. 704,223

1 Claim. (Cl. 260-3971) This application is a division of copendingapplications Serial No. 215,026, filed March 10, 1951 now abandoned, andSerial No. 247,563, filed September 20, 1951.

This invention is concerned with novel chemical compounds of thecyclopentanopolyhydrophenanthrene series and processes for preparing thesame; more particularly, it relates to novelcyclopentanopolyhydrophenanthrene compounds having functionalsubstituents in ring C; and specifically it relates to new compoundshaving a hydroxyl or keto substituent at the 11 position, and toprocesses for the preparation of such compounds.

Compounds of the adrenal cortex, such as Kendalls Compound E(cortisone), have been found to be of great value in the treatment ofvarious diseases. Further, it is likely that Kendalls Compound E and/ orother closely related ll-hydroxy steroids will find increasingtherapeutic use in the future. Unfortunately, the only method for thepreparation of such compounds presently available utilizes desoxycholicor cholic acids as the starting material. Cholic and desoxycholic acidshave hydroxy substituents in ring C at the l2-position, thus providing ameans for introducing a functional substituent'at the 11 position.However cholic and desoxycholic acids, which are obtained from animalbile, are only available in limited amounts. Heretofore no practicalmethod was available whereby a functional group could be introduced inring C which would permit the use of more abundant steroids such as thesterols, ergosterol, cholesterol, stigmasterol, or plant sapogenins,such as diosgenin, tigogenin, and the like.

It is an object of the present invention to provide a process forintroducing a functional group in ring C at the 11 position. It is afurther object to provide a process for convertingcyclopentanopolyhydrophenanthrene compounds having a double bond in the7:8 position to the corresponding cy-clopentanopolyhydrophenanthrenecompound having a hydroxyl or keto group at positions 7 and 11. Anotherobject is to provide new compounds of the steroid series havingfunctional groups in ring C suitable for the preparation of othercyclopentanopolyhydrophenanthrene compounds. Other objects will beapparent from the detailed description hereinafter provided.

In accordance with our invention, we have now found that compounds ofthe cyclopentanopolyhydrophenanthrene series having an ll-ketosubstituent can be synthesized by reactions indicated as follows:

2 ,854,463 Patented Sept. 30, 1958 VII These reactions are carried outas follows:

A cyclopentanopolyhydrophenanthrene compound having a 7:8 double bond(1) is reacted with mercuric acetate producing the correspondingcompound having conjugated double bonds in the 7:8 and 9:11 positions(II) which is treated with a per acid, thus forming an epoxiderepresented by the alternate Formulas IIIA and IIIB. (At present theexact structure of the epoxide is not known and it is represented by thealternative forms IIIA and IIIB. Alternatively it is possible that theproduct obtained is a mixture of these two forms.) This epoxide is thentreated with an adsorbent to form the corresponding A -7,11-dihydroxycompound (IV).

The A -7,11-dihydroxy compound (IV) is reacted with an oxidizing agentto convert the hydroxy substituents to keto groups, thus obtaining thecorresponding A -7,11- diketo cyclopentanopolyhydrophenanthrenederivatives (V). These diketo compounds are then reduced to saturate theA double bond and form the corresponding 7,1l-diketo compound VI. Thesaturated diketo compound is then reduced to eliminate the 7-ketosubstituent, thus producing the corresponding ll-keto compound (VII).The latter compounds are useful intermediates for the preparation ofll-keto compounds having desirable therapeutic properties.

The A -compounds of the cyclopentanopolyhydrophenanthrene series areconveniently prepared by reacting the corresponding A' -compound withmercuric acetate. We have found that this reaction is preferablyeffected by reacting the A' -compound with mercuric acetate and glacialacetic acid in the presence of a suitable solvent medium such aschloroform. The reaction is conveniently conducted by stirring thereaction mixture for 16-24 hours. After the reaction is completed, the K-compound is recovered fromthe reaction mixture by removing theprecipitated mercurous acetate, and concentrating the solution underdiminished pressure. If desired, the residue may be further purified bycrystallization from suitable solvents. Thus, this process can beutilized to prepare A' -pregnadiene-3-ol-20-one-3- acetate, and A-dehydrotigogenin acetate from A pregnenolone acetate and A'-dehydrotigogenin acetate respectively. Alternatively, other acylderivatives of these starting materials or the S-hydroxy compounds maybe utilized as starting materials in our process to prepare thecorresponding A -compunds.

Further, the 3-hydroxy-A' -choladienic acid, which is also useful as astarting material in the processes of our .invention, is readilyobtained by reducing, the 3-hydroxy-12-keto-A -choladienic acid. This isconveniently accomplished by reacting the keto acid with hydrazinehydrate and an alkali metal hydroxide .in the presence of a suitablehigh boiling solvent such as diethylene glycol.

This invention is concerned with compounds of the type represented byintermediate VII above, and with the processes of producing the same.Compound VII may be presented by the following formula:

The starting materials used in the process of this invention, namely,the 7,11-diketo compounds shown by Formula VI, may be obtained asdescribed in copending application, Serial No. 215,026, filed March 10,1951.

Pursuant to our invention, we have found that the 7,1'1-diketocyclopentanopolyhydrophenanthrene compounds can be reduced to thecorresponding ll-keto compounds. We prefer to effect this reduction byreacting the 7,11-diketo compound with hydrazine hydrate and an alkalimetal hydroxide at elevated temperatures in a high boiling solventmedium, for example, diethylene glycol. It is surprising that underthese reaction conditions the ll-keto group is not simultaneouslyreduced along with the 7-keto group. On the contrary, we have found thatunder optimum conditions excellent yields of the desired ll-ketocompounds are obtained by this reduction process.

Thus, in accordance with the processes described above3-hydroxy-1l-keto-A -ergostene, 3-hydroxy-11- keto-bisnorallocholanicacid, 3-hydroxy-1l-ketotigogenin, and the corresponding esters, acylderivatives, or esterified acyl derivatives can be prepared from thecorresponding 7,11-diketo compounds. If desired, these 3-hydroxy-11-keto compounds may be oxidized to obtain the 3,11- diketo compounds inaccordance with methods known in the art.

The ll-keto cyclopentanopolyhydrophenanthrene compounds obtained by theprocesses of our invention can be used as starting materials in thepreparation of other steroid compounds such as Kendalls Compound E orCompound F.

The following examples are presented to illustrate specific embodimentsof our invention.

EXAMPLE 1 Preparation of 3-hydroxy-1l-keto-A -ergostene from3-acetoxy-7,Il-diketo-A -ergostene A mixture of 1 g. of3-acetoxy-7,1l-diketo-A -ergostene, -cc. of diethylene glycol, 0.455 g.powdered potassium hydroxide and 0.5 cc. of 85% hydrazine hydrate washeated at 'atemperature of 132? C. for 1 hour. The temperature wasthenraised to 190-200" C. and the reaction mixture was held at thistemperature for 2 hours. Water was allowed to distill 01f during thisheating period. t y

, Fifteen cubic centimeters of water were added to the cooled reactionmixture and then the dark brown suspension was acidified withhydrochloric, acid and filtered. The brown product was dissolved in hotacetone,:fi1tered and then treated with charooal1(Darco) and filtered.

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The solvent was evaporated in a stream of nitrogen and the residuedissolved in 25 cc. of benzene and chromatographed on 20 g. of acidwashed alumina.

The column was developed with the following solvents:

Benzene Ether Methanol Ethyl acetate Chloroform Acetone The benzenefractions yield a brown amorphous solid. All other fractions were empty,or gave brown tars.

The brown amorphous material was dissolved in 30 cc. of benzene and 10cc. of petroleum ether added and the solution chromatographed on 20 g.of acid washed alumina. The chromatograph was developed with thefollowing solvents:

Petroleum ether/benzene 1:3 Benzene Ether Methanol From the etherfractions 150 mg. of crystalline 3-hydroxy-1l-keto-A -ergostene wasobtained which on recrystallization from methanol melted at 173-l74 C.[a] =+26.6; a=0.485; C=0.91% CHCl Analysis.-Calc. for C l-1 0 C, 81.10;H, 11.7. Found: C, 81.72; H, 11.29.

3.175 grams of 3-hydroxy-11+keto-A -ergostene was refluxed with 20 cc.of acetic anhydride for 1 hour. 011 cooling to room temperature the3-acetoxy compound crystallized out. It was filtered and washed withalittle cold methanol. Yield 2.685 g. M. P. 122-424 C. --A small sampleof 3-acetoxy-11-keto-A -ergostene recrystallized from methanol melted at129.5131.5 C.

Analysis.-Calc. for C H O C, 78.90; H, 10.59. Found: C, 78.95; H, 10.82.I

3-acetoxy-11-ketobisnoralloch0lanate.

2.36 grams of 3-acetoxy-ll-keto-a -ergostene was dis solved in 75 cc. ofchloroform and treated with ozone at 0 'C. The reaction mixture .wasdiluted with cc. of glacial acetic acid and oxidized atroom temperaturewith 1 g. of chromic acid dissolved in 1 cc. of water and 50 cc. of.glacial acetic acid. Five cubic centimeters'of methanol were addedtodestroy excess chromic acid and the solvent 'was removed in vacuo toalmost dryness.

The residue in the'fiask was dissolved by shaking twice with a mixtureof 100cc. of benzene and 50 cc. of 5% sulfuric'acid. The combinedaqueous acid solution was extracted with an additional 50 cc. ofbenzene. The combined benzene extracts were washed with 50 cc. of waterand dried over anhydrous magnesium sulfate. The benzene was removed invacuo and the residue dissolved in 250 cc. of ether.

The ethereal solution was stirred with 5 g. of anhydrous sodiumcarbonate and 10 cc. of water for 45 minutes. The other layer wasremoved by decantation and *the aqueous layer washed twice bydecantation with ether.

The aqueous layer was acidified with 50% sulfuric acid and the liberatedacid 3-acetoxy-1l-keto-bisnorallocholanic acid wasextracted into etherand separated from the aqueous layer.

The ethereal solution of the acidwas treated with an ethereal solutionof diazomethane and the ether evaporated to small volume on the steambath whereupon the methyl ester crystallized out. Yield 750 mg.Recrystallized from methanol the substance, methyl 3-acetoxy-11-ketobisnorallocholanate, melted at 191l94 C.

Analysis-Cale. for 0 1-1 0 C, 71.73; H, 8.91. Found: C, 71.89; H, 9.15.

5 EXAMPLE 3 Preparation of methyl 3,11-diketbisnorallocholanate from3-acet0xy-11-ket0bisnorall0ch0lanate 750 mg. of methyl3-acetoxy-1l-ketobisnorallocholanate (prepared as shown in Example 2)was refluxed with 30 cc. of potassium hydroxide for one half hour. Fiftycubic centimeters of water were added, the precipitated product wasfiltered and washed with Water. The product, methyl3-hydroxy-l1-ketobisnorallocholanate, melted at 176-l78.5 C.

The 3-hydroxy compound was dissolved in approximately 30 cc. of acetoneand oxidized at room temperature by addition of 200 mg. of chromiumtrioxide in 5 cc. of 1 N sulfuric acid. The oxidizing agent was addeddropwise with stirring over a period of one half hour. 'The reactionmixture was stirred an additional minutes, 1 cc. of methanol was addedand the precipitated chromium salts filtered ofi.

The acetone solution was diluted with approximately 100 cc. of waterwhich precipitated the product. After cooling, the product was filtered0E and washed with water. Recrystallized from acetone the substance,methyl 3,11-dil etobisnorallocholanate, melted at 201-204 C. Mixedmelting point with an authentic sample 201-204 C. Mixed melting pointwith the cisisomer 171-193 C. Yield, 250 mg., 37% yield; [a] =+63.

Analysis-Calc. for C H O C, 73.96; H, 8.90. Found: C, 74.18; H, 9.20.

EXAMPLE 4 Methyl 3-hydroxy-11-keto-bisnorallocholanate OOOH A00 1 =0 H OIII IV One gram of 3-acetoxy-7,1l-diketo-A -ergostene (I) obtained asdescribed in copending application Serial No. 215,026, filed March 10,1951, was dissolved in 100 cc. of chloroform and ozone was passedthrough at ice bath temperature until the approximate theoretical amountof ozone was absorbed. The reaction mixture was diluted with 100 cc. ofglacial acetic acid, cooled to 5 C. and oxidized with 0.5 g. chromicacid dissolved in 0.75 cc. water and 50 cc. glacial acetic acid.

After standing overnight, 5 cc. of methanol was added and the solventwas removed in vacuo to practically dryness. The residue in the flaskwas dissolved by shaking twice with a mixture of 25 cc. of 5% sulfuricacid and 50 cc. of benzene. The combined benzene solutions were driedover anhydrous magnesium sulfate, and the benzene was evaporated on thesteam bath in a stream of nitrogen.

The residue was dissolved in 200 cc. of ether and stirred with 5 g. ofsodium carbonate and 2 cc. of water for 21 hours. The sodium salt of3-acetoxy-7,l1-diketobisnorallocholanic acid (II) was filtered off anddried in a vacuum desiccator.

The dried sodium salt was suspended in 25 cc. of ether and 25 cc. of 50%sulfuric acid was added in small portions until the mixture wasdefinitely acid. cc. of ether was added to bring about complete solutionof all solids. The aqueous layer was separated and extracted once with50 cc. of ether.

The combined ethereal solutions were dried over anhydrous magnesiumsulfate and then evaporated on the steam bath to a small volume,whereupon 3-acetoxy-7,11- diketo-bisnorallocholanic acid (II)crystallized out. The product was recrystallized from ether; M. P.235-238 C. [a] =24.6; a=0.68; C -1.38% OHCI Analysis.-Calcd for C H O C,68.87; H, 8.19. Found: C, 68.67; H, 8.04.

Mg. of 3-acetoxy-7,1l-diketo-bisnorallocholanic acid was suspended in 25cc. of ether .and esterfied with diazomethane. All solid dissolved andon evaporation of the ether to a small volume, the methyl ester (I-II)crystallized. M. P. 226.5-229 C. Mixed melting point with an authenticsample of the ester: 227230 C. a

5 g. of methyl 3-acetoxy-7,11-diketo-bisnorallocholanate (HI) and 2.07g. of powdered potassium hydroxide were placed in a 50 cc. round-bottomflask. 25 cc. of diethylene glycol and 2.3 cc. of 85% hydrazine hydratewere added and the temperature raised to ISO- C. and held for 1 hour.The temperature was then raised to 195-200" C. and held for 2 hours.

After cooling, the reaction mixture was dissolved in benzene and water,50% sulfuric acid added until an acid reaction was obtained. The benzenelayer was separated, and the aqueous layer extracted three times with 50cc. of benzene. The combined benzene solutions were washed with waterand dried over anhydrous magnesium sulfate.

The benzene was treated with Darco. The benzene solution wasconcentrated in vacuo to dryness, the residue was dissolved in ether andesterified with an ethereal solution of diazomethtane. The ether wasevaporated, and the methyl 3-hydroxy-11-keto bisnorallocholanate (IV)was recrystallized from methanol, M. P. 177.5-180.5. Mixed M. P. with anauthentic sample, 177-179 C. [05] D23:

EXAMPLE 5 Preparation of 3-hydr0xy-11-ket0bisn0rall0ch0lanic acid andits methyl ester from 3-acet0xy-7,1J-diketobisnorallocholanic acid Twograms of 3-acetoxy-7,1l-diketobisnorallocholanic acid (prepared asdescribed in Example 4) were stirred in a 50 cc. round bottom flask with15 cc. of diethylene glycol, 1.5 g. of powdered potassium hydroxide and1.5 cc. of 85% hydrazine hydrate and the temperature raised slowly to135-140 C. and held for 45 minutes. The temperature was then raised to190-195 C. and held for one hour.

After cooling the reaction mixture was acidified with 2 N sulfuric acid,diluted with 30 cc. of distilled Water and filtered. The tan, dried cakeweighed 1.57 g. The product was dissolved in benzene-ethanol, treatedwith Darco, filtered through Supercel and the filtrate was concentrateduntil crystallization started. Recrystallization from benzene gave 0.60g. of product melting at 258 to 261.4 C.

Analysis.Calcd for C H O C, 72.89; H, 9.45. Found: C, 72.82; H, 9.34.

An additional 0.60 g. of lower melting acid (M. P. 252-258) wasrecovered from the mother liquors of the above product.

A sample of the acid was esterified with diazomethane in etherealsolution to give methyl 3-hydroxy-11-keto bisnorallocholanate (III)melting point -177.5, [a]

EXAMPLE 6 Preparation of ll-ketotigogenin from 3-acetoxy-7,1I-

diketotigogenin A mixture of 0.42 'g. of 3-acetoxy-7,l1-diketotigogenin,

2.1 ml. of diethylene glycol, 0.20 g. of powdered potassium hydroxide,and 0.21 ml. of hydrazine hydrate (85%) was stirred while being heatedin an oil bath. The temperature was raised to 12030' C. and held therefor fifteen minutes. The temperature was then raised .to l95-200 C. for45 minutes. After cooling, the mixture was poured into 25 ml. of icewater mixture and the resulting mixture was neutralized with dilutesulfuric acid. The solid product was removed by filtration and waswashed well with water. The. dried crude product was dissolved in 20 ml.of methanol, and boiled for five minutes with a small amount ofactivated charcoal. After removing the charcoal by filtration, themethanol solution was concentrated to tenml. Water was added to the hotsolution until crystallization was incipient.

8 Upon cooling, 0.22 g.. of ll-ketotigogenin in the form of needles wereobtained, M. P. 220-226 C. Recrystallized from a mixture of ethylacetate-petroleum ether, the product melted at ZZZ-226 C.

Analysis.Calcd for 0 1-1 0 C, 75.31; H, 9.83. Found: C, 75.40; H, 10.20.

1 ll-ketotigogenin acetate was made by refluxing 11- ketotigogenin withacetic anhydride. Recrystallized from methanol, it'melted at 224-229 C.

Various changes and modifications may be made in carrying out thepresent invention without departing from the spirit and scope thereof.Insofar as these changes and modifications are within the purview of theannexed claim, they are to be considered as part of our invention.

We claim:

A process forthe conversion of a lower alkyl 3-lowercarboxyacyloxy-7,11diketo-cholanate to the corresponding lower alkyl3-lower carboxyacyloxy-ll-keto-cholanate, which comprises reacting thelower alkyl 3-lower carboxyacyloxy-7,l1-diketo-cholanate with hydrazinehydrate and an alkali.

No references cited.

